The present invention relates to the production of building or construction members constituted by wooden beams or girders forming a framework onto which is moulded a concrete slab or plate. It more particularly relates to the connection between the wooden beams or girders and the concrete slab or plate.
This composite wood-concrete construction is known. Generally a metal lattice embedded in the concrete slab ensures the resistance of the latter to perforation and to transverse bending stresses. Moreover, connectors fixed in the wood and concrete act in the manner of stirrups in a reinforced concrete beam preventing any displacement in the longitudinal direction of the beams.
Numerous improvements have been made to the junction between the various components of this type, particularly as a result of them being made from materials of different types.
Thus, the junction can be provided by vertical nails driven into the upper faces of the beams, the heads of said nails being embedded in the concrete.
Sheet metal plates fixed in the flanks of joists and cut so as to form teeth embedded in the concrete after traversing the shuttering have been used (POUTANEN-TUOMO-TAPANI EP-A1-104,629).
Another type of connection uses connectors formed from cylindrical tubes fixed in the upper face of the wooden beam (PARIS OUEST FR-A-2,611,778 and EP-A-280,228).
It is also known to use a sheet metal strip for providing a connection between two wooden beams. The metal sheet constitutes a core between the two beams in which it is fixed (FALKENBERG EP-B1-38,830).
Although these constructions bring about certain improvements in the prior art, they still suffer from disadvantages. In particular the use of metal sheets fixed in the flanks of joists leaves visible metal parts which is disadvantageous from the construction esthetic standpoint. In addition, teeth embedded in concrete do not constitute adequate connecting surfaces in order to withstand high longitudinal stresses.
The use of cylindrical connectors also requires fixing in the wood of a meticulous nature and may require the use of glue. A vertical sliding can also occur between the connector and the slab in the case of repeated alternating loads.
Generally there is no connection with the metal lattice or fittings embedded in the concrete. The use of presses liable to exert significant stresses for fixing the connectors in the wood can be prohibitive in certain cases, particularly when fixing must take place on site.
The storage and handling of beams with projecting connectors can be difficult both as a result of their fragility and as a result of work safety risks.
The object of the present invention is to obviate the aforementioned disadvantages of the prior art, so as to be usable without difficulty on the works site and without any major risks occurring during handling operations.